Healthy horses and other animals have large numbers of resident leukocytes in the intestinal wall, but there is scant information regarding which and how many leukocytes are normally present in the equine intestinal wall. Our aim was to provide a reference range of leukocytes in the intestinal mucosal and submucosal propria of normal horses. We included in our study intestinal tissues from 22 Thoroughbred racehorses with no clinical intestinal disease, which had been euthanized because of catastrophic musculoskeletal injuries. Neutrophils, lymphocytes, eosinophils, macrophages, and plasma cells were counted in 5 random 17,600-µm² areas of villus lamina propria of the duodenum, jejunum, and ileum, and deep lamina propria of the duodenum, jejunum, ileum, right ventral colon, left ventral colon, left dorsal colon, right dorsal colon, and small colon. Other features investigated in the same intestinal segments included villus height and width (small intestine), presence of ciliated protozoa, Paneth cells number, subcryptal leukocyte layers (number of leukocyte layers between the bottom of the crypts and the muscularis mucosae), and submucosal leukocytes. Lymphocytes were the most numerous cells in all segments analyzed, followed by plasma cells, eosinophils, macrophages, and neutrophils. Eosinophil numbers were significantly higher in both lamina propria and submucosa of the large intestine than in the small intestine. The duodenum had shorter and thinner villi than either jejunum or ileum. The data provided from our study will be useful for diagnosticians examining inflammatory processes in the intestinal tract of horses.

健康的马和其他动物的肠壁中有大量常驻白细胞，但关于马肠壁中通常存在哪些白细胞和多少白细胞的信息很少。我们的目的是为正常马的肠黏膜和黏膜下固有层中的白细胞提供一个参考范围。我们在研究中纳入了来自 22 匹没有临床肠道疾病的纯种赛马的肠道组织，这些赛马因灾难性的肌肉骨骼损伤而被安乐死。中性粒细胞、淋巴细胞、嗜酸性粒细胞、巨噬细胞和浆细胞在 5 个随机 17,600-µm ^2中计数十二指肠、空肠和回肠的绒毛固有层区域，以及十二指肠、空肠、回肠、右腹结肠、左腹结肠、左背结肠、右背结肠和小结肠的深层固有层。在相同肠段中研究的其他特征包括绒毛高度和宽度（小肠）、纤毛原生动物的存在、潘氏细胞数量、隐窝下白细胞层数（隐窝底部和黏膜肌层之间的白细胞层数）和黏膜下白细胞. 在所分析的所有部分中，淋巴细胞是数量最多的细胞，其次是浆细胞、嗜酸性粒细胞、巨噬细胞和中性粒细胞。大肠固有层和黏膜下层的嗜酸性粒细胞数量明显高于小肠。十二指肠的绒毛比空肠或回肠短且薄。我们研究提供的数据将有助于诊断人员检查马肠道中的炎症过程。